The present invention relates to a multi-functional press for welding plastic tubes and joints, particularly polyethylene PE, polypropylene PP, polybutene PB and polyvinyldifluoride PVDF tubes and joints.
More specifically, the invention concerns a press of the above kind, usable on a bench either in a workshop or directly with the building yard, said press being useful both for discharge systems and pressure systems.
As it is well know, the problem of welding plastic tubes, and particularly welding of deviation joints and special pieces on a main duct, independently from the dimensions, is extremely felt since the worker would always like to easily carry out optimum and perfectly aligned and concentric weldings.
In fact, there exist on the market bench apparatuses to carry out this kind of welding, none of them being able to easily guarantee a coaxial and perfectly aligned welding.
Until a certain period, this kind of imprecision, that can be partially compensated for by the experience of the operator, even if it is a drawback, was deemed to be not resolvable, particularly for short derivations directly coupled on the flank of a tube, since the weldings were intrinsically defective.
In fact, before the filing of the Italian patent No1,231,685, of May 18, 1989, originally filed in the name of the same Applicant, reduction derivations had a circular cross-section, so that weldings obtained were in any case defective.
By the structure of the new joints described and claimed in said Italian patent, presently sold by MKM S.r.l., it has been made it possible to obtain structurally perfect weldings, but in this case, apparatuses presently available do not allow to exploit at best the joint features.
On the other hand, there exist on the market apparatuses solely studied to make head weldings providing a fixed vise and a vise movable on a base, between which the fusion mirror and the milling machine are introduced, according to the working step.
The present invention relates to a multi-functional press for welding plastic tubes and joints, particularly polyethylene (PE), polypropylene (PP), polybutene (PB) and polyvinyldifluoride (PVDF) tubes and joints.
More specifically, the invention concerns a press of the above kind, usable on a bench either in a workshop or directly with the building yard, said press being useful both for discharge systems and pressure systems.
As it is well know, the problem of welding plastic tubes, and particularly welding of deviation joints and special pieces on a main duct, independently from the dimensions, is extremely felt since the worker would always like to easily carry out optimum and perfectly aligned and concentric weldings.
In fact, there exist on the market bench apparatuses to carry out this kind of welding, none of them being able to easily guarantee a coaxial and perfectly aligned welding.
Until a certain period, this kind of imprecision, that can be partially compensated for by the experience of the operator, even if it is a drawback, was deemed to be not resolvable, particularly for short derivations, directly coupled on the flank of a tube, since the weldings were intrinsically defective. In fact, before the filing of the Italian patent No. 1,231,685, of May 18, 1989, originally filed in the name of the same Applicant, reduction derivations had a circular cross-section, so that weldings obtained were in any case defective.
By the structure of the new joints described and claimed in said Italian patent, presently sold by MKM S.r.l., it has been made it possible to obtain structurally perfect weldings, but in this case, apparatuses presently available do not allow to exploit at best the joint features.
On the other hand, there exist on the market apparatuses solely studied to make head weldings providing a fixed vise and a vise movable on a base, between which the fusion mirror and the milling machine are introduced, according to the working step.
Said apparatuses, that can be used only for the head weldings, have functionality limits, one of which is maintaining perfectly concentric or aligned the two ends to be welded (co-axiality and concentricity).
Another problem of this kind of apparatus is that both the mirror and the milling machine remain within the ray of action of the apparatus, thus not allowing free working, a particularly important consideration when tubes already provided with derivations are worked, and more particularly in case of multiple and/or opposed and close each other derivations, and with part of already lengthened sections.
Thus, different kinds of weldings exist that should be carried out, on the basis of the presently available techniques, employing different apparatuses.
In fact, besides the realisation of the head weldings for pre-pressed tubes or special pieces, and to the realisation of the derivation weldings employing the above mentioned MKM joints, inclined weldings, and parts of sectors to make curves, are realised; and in the poly-fusion technique the so called socket and pocket weldings.
To realise the above, the operator should be provided with a plurality of apparatuses that besides the costs problem, are not practical, particularly when realising them directly with the building yard.
EP 0543903 describes an apparatus according to the pre-characterising portion of claim 1.
In view of the above, the applicant has realised a multi-functional universal press that is able to carry out all the above mentioned operations in a single apparatus.
It is therefore a specific object of the present invention to provide a multi-functional press for welding plastic tubes and joints, particularly polyethylene (PE), polypropylene (PP), polybutene (PB), and polyvinyldifluoride (PVDF) tubes and joints, comprising a first fixed base and a second base, movable with respect to said first base along sliding guides, a first vise group, mounted on said first base and a second vise group mounted on said second base, characterised in that it further provides a thermo-element, provided on a guide parallel with respect to said first and second base, and coupled with said guide in such a way to be provided in a working position between said vise groups, and in a rest position, completely out of the operation field of said vise groups, and in a lowered position with respect to the operation field of said vise groups, and in that said vise groups are mounted on the relevant fixed and movable base, in such a way to be also able to rotate and to take every orientation with respect to the base axis.
According to the invention on said guide parallel to said first and second base a milling machine can be provided, in the same way of said first element.
Preferably, according to the invention, means are provided indicating the orientation of the vise group with respect to the relevant base.
Still according to the invention, said vise groups each have a pair of vises, said vises of each group being movable relative to each other to vary the distance between the two vises of each base.
Still according to the invention, said vise group mounted on said movable bases can provide a single vise, and a drilling machine, provided at the back with respect to the vise, to drill the main tube on which a derivation is welded.
Always according to the invention, every vise of said groups will provide two openable and closable asymmetric parts, in each of said semiparts being provided an eccentric adapter, to adapt to the specific tube under work, maintaining the surface of the tube in a constant and well aligned position.
Furthermore, according to the invention, in case a socket welding is carried out, an adapter suitable to support the socket or pocket element will be provided on the inner vise of the vise group provided on the movable base.
Still according to the invention, approaching and moving away means will be provided on said fixed base, for moving the movable base, as well fixing means will be provided to fix the movable base in the proper position, buckling elastic means being provided on said movable base, said means determining the loading pressure for the head weldings, and pin means to exclude said buckling elastic means when carrying out socket or pocket weldings.
According to the invention, said thermo-element can be a mirror or polifusion element, provided with a thermocouple electronic control, said thermo-element being interchangeable without being necessary to replace the support and the control system.
Furthermore, according to the invention, the press can provide a drawer to place the fittings.